"since" + present perfect

Tom   Wednesday, May 14, 2003, 12:01 GMT
I've just heard the following line in a song:

It's only been three days since I have seen your face.

How do you feel about this sentence? Shouldn't it say "It's only been three days since I _saw_ your face?"
Nora   Wednesday, May 14, 2003, 12:12 GMT
I've studied that it is right to say:
I've known my best friend since 10 years.
Simon   Wednesday, May 14, 2003, 12:22 GMT
No, I've known my friend for 10 years.
Nora   Wednesday, May 14, 2003, 12:44 GMT
It seems that I've forgotten everything since I've studied english.
but is it possible to say my sentence.
This grammar is hard cheese for me. I have no sence for grammar.
Just write the words - they comes without thinking of any rules. I have no longer practice. It's boring.
mjd   Wednesday, May 14, 2003, 17:07 GMT

The sentence seems okay, but I'd say your sentence flows better and sounds more natural. It's certainly what I would say.